Popular Stories

Real Estate For Sale

IT IS an old topic and my comments are directed to us all as a refresher for our assessment and action steps taken on helicoverpa grubs in mung beans. From my recent inspections we have plenty of helicoverpa in many of our crops, including slightly unusually in lucerne blocks and, of course, mung beans.

This early entry by the female moths into basically our current vegetative mung bean crops is not new, however it needs inspection and a decision if control of larvae is required.

Let me say, with these early grub numbers into mung bean crops it is not easy to decide on an action course and I have found myself changing my mind three times on the way out of the paddock over the years.

We now have a threshold of four to five per square metres in this pre-axillary buds stage of growth, providing you manage to count them all.

I am okay with this threshold, however I do keep in mind that about 30% leaf defoliation threshold is not that easy to judge and targeting smaller larval size is critical, if using NPV or the old BT in the control management process.

So while we have the above threshold, like a lot of things in agriculture, it should reflect the view that all is not black and white and you need some understanding of soil moisture levels and compensatory growth of these leguminous plants.

I have mentioned the two biological insecticides we have all successfully used in different crops over the years and yet I can recall some of the fairly large failures of either product, targeting a range of sized entrenched grubs in the reproductive stage of flowering, to late pod fill.